A friend of mine insist that as long as the voltage on an ac adapter matches what the device requires, you can plug it in and see if it works without harming the device. He says that it will either work or it won't work.

Now from what I understand, it may or may not work, yes, but if it DOES work, there could be a chance of the power supply or the device getting too much/too little amperage, causing one of them to 'work harder' and overheat/start fire.

I'm not sure myself on this subject, but my googling-skills apperently seem to be lacking lately.

Can anyone point me to a definitive article/wiki that explains the dangers (if any) of using different ac adapters with varying Amps vs. what the device requires.

Power supplies do not force amperage on a device. Devices are designed to run at a specified voltage, and they use a specified amount of amperage at that voltage. A well designed power supply will provide a specified voltage up to its rated current limit. Some supplies also require a minimum current draw to remain stable.

Consider voltage as water pressure and current as the rate of current flow from the supply. The supply is essentially a resevoir that will provide current at the specified pressure up to the maximum current limit of the supply.

For parallel example, you can plug as many 120 volt AC devices as you want into a given circuit on your house wiring UP TO the limit imposed by the fuse for that circuit. Drawing less than that limit won't do anything but run up your power bill, but you can't exceed the limit imposed by the fuse.

Not all supplies are regulated, and the voltage from unregulated supplies can vary with the load (number of amps drawn). As long as the supply is regulated, you can use it for any device that uses UP TO the specified limit.

Be careful of one other issue. There is no standard for which of the contacts is positive and which is negative. Usually, the outer sleeve is negative and the inner pin is positive, but not always. Be very sure the supply you want to use has the same contact assignment as your device.

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Originally posted by: Harvey
Power supplies do not force amperage on a device. Devices are designed to run at a specified voltage, and they use a specified amount of amperage at that voltage. A well designed power supply will provide a specified voltage up to its rated current limit. Some supplies also require a minimum current draw to remain stable.

Consider voltage as water pressure and current as the rate of current flow from the supply. The supply is essentially a resevoir that will provide current at the specified pressure up to the maximum current limit of the supply.

For parallel example, you can plug as many 120 volt AC devices as you want into a given circuit on your house wiring UP TO the limit imposed by the fuse for that circuit. Drawing less than that limit won't do anything but run up your power bill, but you can't exceed the limit imposed by the fuse.

Not all supplies are regulated, and the voltage from unregulated supplies can vary with the load (number of amps drawn). As long as the supply is regulated, you can use it for any device that uses UP TO the specified limit.

Be careful of one other issue. There is no standard for which of the contacts is positive and which is negative. Usually, the outer sleeve is negative and the inner pin is positive, but not always. Be very sure the supply you want to use has the same contact assignment as your device.